It is often necessary to connect electrically two components separated by a hinge. In some cases the object sets particular requirements to the device, such as in the case of PDA (Personal Digital Assistent) -type mobile station applications. In order to improve their usability it is common to strive for as small a size as possible and as a result of this desire for miniaturizing are tried to make the housing of a mobile station and its parts as small as possible. If the two parts separated by hinges of a mobile station of a hinged construction comprise components to be connected to each other using conductors, certain problems are met, which problems culminate due to the miniaturizing. The bending radius of a conductor to be threaded through a hinge becomes smaller as the hinge becomes smaller. The cable between the hinged parts is subject to repeated bending. Still the cable should not be chafed, tensioned, nor be bent at too short a stretch in order to not get its cord or isolation damaged. The cable must be sufficiently flexible to tolerate the repeated deformations it is exposed to and it further has to fit in the lead-through reserved for it. In a mobile station, the radio frequency signals of which are transferred from one hinged part to another, a coaxial cable is used for this purpose.
It is prior known from Fl Patent Application 956225 such a hinged device, in which a tubular middle piece has been placed on the hinge axis, through which middle piece the cable runs perpendicularly or obliquely. The arrangement is particularly suitable to be used in PDA -devices for very flexible, flat cable type conductors, and if the diameter of the middle piece is big enough, it can also be used as a coaxial cable lead-through from the base part to the folding part. A coaxial cable does not tolerate bending as well as a cord made of thin copper strands.
It is prior known from U.S. Pat. No. 4,571,456 a portable computer shown in FIGS. 4a and 4b comprising base part 22 and display unit 23, and cable 24 between the base part and the display unit. Display unit 23 has been arranged to fold in relation to base housing 22 using hinge construction 25. Cable 24 passes through the hinge parallel to the hinge axis. The hinge construction shown in FIG. 4a is situated in the edge of the cover of the portable computer and cable 24 has been thread into a groove in the base housing side halve of the hinge and is protected by the part of the portable computer. In a hinge according to the construction, cable 24 is thus enveloped by the hinge section of the display unit and the hinge section is further surrounded by the hinge casing of the portable computer, in which casing said display unit hinge section turns. The hinge construction thus is quite sizable, and particularly if the ends of cable 24 have been provided with pre-mounted connectors and because of these an even larger space has to be left in the middle of the hinge in order to allow to thread a cable end with a connector through the hinge in the assembly stage.
In so called Organiser-type devices it also has been used a hinge construction in which the cable lead-through has been realized perpendicularly to the hinge axis, in which case the bending radius of the cables is small and their bending angle is as big as the unfolding angle of the device. This may cause stress on the cables and in addition to that some slack must be left in the cables. Increasing the deformation area of the cable decreases the stress and from U.S. Pat. No. 5,141,446 such a solution is known, in which a flat cable has been loosely coiled around an axis inside a tube. The flat cable coils around the axis when the hinge is used, in which case the strain on the flat cable is distributed in the flat cable on one full turn around the axis. The required slack in turn stays inside the tube. The hinge construction according to the patent, however, is largish because between the axis and the tube there must remain room well over the thickness of the flat cable, and in the assembly stage the required slack must be left inside the construction.